Tag Archives: particulate

Leaf blowers are not only annoying but also bad for you (and the environment)

The seemingly-innocuous leaf blower may actually cause a lot more damage than you’d think — to both your health and the climate.

A groundskeeper blows autumn leaves in the Homewood Cemetery, Pittsburgh.
Image via Wikimedia.

It’s that time of the year: trees are shedding their leaves, and people are blowing them off the pavement. According to the Centers for Disease Control and Prevention (CDC), this quaint image actually hides several health concerns for operators and the public at large.

The inefficient gas engines typically used on leaf blowers generate large amounts of air pollution and particulate matter. The noise they generate can lead to serious hearing problems, including permanent hearing loss, according to the CDC.

Sounds bad

Some noise may not seem like much of an issue, but the dose can make it poison. The CDC explains that using your conventional, commercial (and gas-powered) leaf-blower for two hours has an adverse impact on your hearing. Some emit between 80 and 85 decibels (dB) while in use. Most cheap or mid-range leaf blowers, however, can expose users to up to 112 decibels (a plane taking off generates 105 decibels). At this level, they can cause instant “pain and ear injury,” with “hearing loss possible in less than [2 to] 5 minutes”.

The low-frequency sound they emit fades slowly over long distances or through building walls. Even at 800 meters away, a conventional leaf blower is still over the 55 dB limit considered safe by the World Health Organization, according to one 2017 study. Because they’re so loud, they can be heard “many homes away” from where they are being used, Quartz explains.

This ties into the greater issue of noise pollution. The 2016 Greater Boston Noise Report (link plays audio,) which surveyed 1,050 residents across the Boston area, found that most felt they “could not control noise or get away from it,” with leaf blowers being a major source of noise. Some 79% of responders said they believed no one cared that it bothered them. Leaf blowers are also seeing more use — in some cases becoming a daily occurrence. As homeowners and landscaping crews create an overlap of noise, these devices can be heard for several hours a day.

Image credits S. Hermann & F. Richter / Pixabay.

With over 11 million leaf blowers in the U.S. as of 2018, this adds up to a lot of annoyed people. Most cities don’t have legislation in place that deals with leaf blower noise specifically, and existing noise ordinances are practically unenforceable for these devices. However, there are cities across the U.S. that have some kind of leaf blower noise restrictions in place or going into effect.

Noisy environments can cause both mental and physical health complications, contributing to tinnitus, hypertension, and generating stress (which leads to annoyance and disturbed sleep).

Very polluting

A report published by the California Environmental Protection Agency (CalEPA) in the year 2000 lists several potential hazards regarding air quality when using leaf blowers:

  • Particulate Matter (PM): “Particles of 10 Fm and smaller are inhalable and able to deposit and remain on airway surfaces,” the study explains, while “smaller particles (2.5 Fm or less) are able to penetrate deep into the lungs and move into intercellular spaces.” More on the health impact of PM here.
  • Carbon Monoxide: a gas that binds to the hemoglobin protein in our red blood cells. This prevents the cell from ‘loading’ oxygen or carbon dioxide — essentially preventing respiration.
  • Unburned fuel: toxic compounds from gasoline that leak in the air, either through evaporation or due to incomplete combustion in the engine. Several of these compounds are probable carcinogens and are known irritants for eyes, skin, and the respiratory tract.

To give you an idea of the levels of exposure involved here, the study explains that landscape workers running a leaf blower are exposed to ten times more ultra-fine particles than someone standing next to a busy road.

Additionally, these tools are important sources of smog-forming compounds. It’s not a serious issue right now, but as more people buy and use leaf blowers, lawnmowers, and other small gas-powered engines, these are expected to overtake cars as the leading cause of smog in the United States.

What to do about it

Well, the easiest option is to use a rake — or just leave the leaves where they are, which is healthier for the environment.

But leaf blowers didn’t get to where they are today because people like to rake. Electrical versions, either corded or battery-powered, would address the air quality and virtually all of the noise concerns (albeit in exchange for less power).

While government regulation might help with emission levels, noise concerns might best be dealt with using more social approaches. Establishing neighborhood-wide leaf blowing intervals, or limiting the activity to a single day per week, would help make our lives a little better. As an added benefit, this would also help people feel that their concerns are being heard, and foster a sense of community.

Researchers estimate the monetary and health cost associated with particulate matter

New research at the University of New Mexico is looking into how much particulate matter air pollution costs the US every year — and how best to tackle it.

Smoke Plume.

Image via Pixabay.

Fine particulate matter (PM2.5) air pollution caused an estimated 107,000 premature deaths in 2011, the study reports. The authors say these deaths cost society at large around $886 billion, and than 57% of them were at least partially the result of pollution caused by energy consumption (i.e. transportation or electricity generation).

Bad air

“The impact of particulate matter air pollution is enormous even in countries with relatively good air quality like the U.S.,” says University of New Mexico economics professor Andrew Goodkind.

“There is still substantial room for improvement to the public health from reducing emissions, even though we have dramatically improved our air quality over the last 40 years.”

PM2.5 are particles with a diameter of or under 2.5 micrometers. They’re exceedingly small, so small, in fact, that we can only see them under an electron microscope. You could string 30 such particles along and they would still be shorter than the diameter of a single one of your strands of hair. Not just invisible to the naked eye, these particles are also quite toxic. They often carry along microscopic amounts of solid or liquid leftovers of the chemical reactions that created the particles themselves — these residues can be quire hazardous to human health.

What makes PM2.5 really troublesome, however, is that they’re so tiny they don’t really decant from they air; they just float around for long stretches at a time. Because of this, they have a very high chance, compared to other pollutants, to make their way into your lungs and bloodstream.

However, the effect of PM2.5 on general health depends greatly on where they are emitted or released. So, Goodkind’s team set about understanding how geography plays a part in their effect.

The team developed a model for calculating location-specific damages due to primary PM2.5 and PM2.5 precursor emissions. Based on these models, the team can estimate the impact of PM2.5 emissions in any location throughout the US, they say. And that’s exactly what they did —  they applied the modeling tool to the U.S. emissions inventory to understand how each economic sector contributes to reduced air quality.

They found that 33% of health damages associated with PM2.5 occur within 8 km of emission sources, but 25% occur more than 150 miles away. These results emphasize the importance of tracking both local and long-range impacts, which is another element of what the paper addresses.

“Sources in the same urban area, releasing the same quantity of emissions, can have orders of magnitude difference in their impacts on health,” Goodkind said. “Identifying those sources with the largest impacts can help improve our decision making about how to reduce pollution.”

The team hopes policymakers will use their results to decide how and where to prioritize pollution mitigation efforts. They also plan to expand on their research by focusing more directly on certain sectors of the economy where emission reductions have been limited.

“Coal-fired electricity generation has, rightly, received substantial attention, and emissions have dropped substantially, but many people do not realize that agriculture is the source of a significant share of emissions,” Goodkind concluded. “We are looking into how and where we grow crops and raise livestock, what inputs are used, and how we can improve the system to continue to produce the food we need but with fewer environmental and health impacts.”

The paper “Fine-scale damage estimates of particulate matter air pollution reveal opportunities for location-specific mitigation of emissions” has been published in the journal Proceedings of the National Academy of Sciences (PNAS).

Air pollution.

Air pollution seems to promote diabetes — even at officially ‘safe’ pollution levels

Air pollution may increase the risk of diabetes — even at levels currently deemed safe.

Air pollution.

Image credits Chris LeBoutillier.

A new study published by researchers from the Washington University School of Medicine in St. Louis and the Veterans Affairs (VA) St. Louis Health Care System suggests that heavily polluted countries such as India or the U.S. could see major health benefits — should they adopt tighter air pollution regulations.

A veterany affair

After sifting through all the research related to diabetes and outdoor air pollution, the team devised a model to evaluate diabetes risk across various pollution levels. They first looked at the levels of particulate matter — microscopic bits of dust, dirt, smoke, soot, and fluids that float around in the atmosphere — as recorded by the EPA’s land-based air monitoring systems and NASA satellites. They focused their research on particulate matter as these materials can pass into the bloodstream from the lungs, contributing to major health conditions such as heart disease, stroke, cancer, or kidney disease.

The team also analyzed data from 1.7 million U.S. veterans (who were followed for a median of 8.5 years). None of the veterans had a history of diabetes. Finally, they analyzed data from the Global Burden of Disease study — conducted annually with contributions from researchers worldwide —  to estimate annual cases of diabetes and healthy years of life lost due to pollution.

All this data was fed through statistical models meant to test whether any link can be observed between air pollution levels and diabetes incidence. The validity of the link was tested through the introduction of two other variables: ambient sodium concentrations, which have no link to diabetes, and lower limb fractures, which have no link to outdoor air pollution. The addition of these datasets helped the team spot any suspicious associations between the pollution and diabetes datasets.

Diabetes is one of the fastest growing diseases worldwide. An unhealthy diet, a sedentary lifestyle, and obesity are considered the main drivers behind the disease — and, according to more recent research, white paint. The findings today, however, suggest that air pollution may also shoulder a large part of the blame:

“Our research shows a significant link between air pollution and diabetes globally,” said Ziyad Al-Aly, MD, study senior author. “We found an increased risk, even at low levels of air pollution currently considered safe by the U.S. Environmental Protection Agency (EPA) and the World Health Organization (WHO).”

“This is important because many industry lobbying groups argue that current levels are too stringent and should be relaxed. Evidence shows that current levels are still not sufficiently safe and need to be tightened.”

The team estimates that air pollution contributed to 3.2 million new cases of diabetes throughout the world in 2016 — about 14% of all cases that year. Pollution-linked diabetes led to the loss of some 8.2 million years of healthy life in the same year, which again corresponds to roughly 14% of all healthy life lost to diabetes overall. In the United States, the study attributed 150,000 new cases of diabetes per year to air pollution and 350,000 years of healthy life lost annually.

The findings suggest that reducing air pollution may also help curb cases of diabetes in heavily polluted countries or areas.

Among the sample of veterans exposed to pollution levels between 5 to 10 micrograms per cubic meter of air, 21% developed diabetes. At exposures of between 11.9 to 13.6 micrograms per cubic meter of air, roughly 24% developed diabetes. In the United States, the EPA-set maximum safe pollution threshold sits at 12 micrograms per cubic meter of air. Al-Aly’s team, however, says that their results show pollution levels as low as 2.4 micrograms per cubic meter of air lead to a noticeably increased risk of developing diabetes.

People in lower-income countries such as India are also at a higher overall risk of pollution-related diabetes. This may come down to these countries lacking resources to invest in environmental mitigation systems or policy. Countries whose citizens are at higher risk of pollution-related diabetes include Afghanistan, Papua New Guinea, and Guyana. Countries such as France, Finland, and Iceland experience a lower risk, while the U.S. sees a moderate risk of pollution-related diabetes.

The paper ” The 2016 Global and National Burden of Diabetes Mellitus Attributable to Fine Particulate Matter Air Pollution” has been published in the journal The Lancet Planetary Health.

Paris takes drastic measures to limit car traffic, in an attempt to fight smog

Paris authorities have put in place 24-hour emergency measures to limit the number of cars in traffic as part of their efforts to fight the smog shrouding the city. Today (Monday, March 23) all cars with number plates that end with an even number will be banned from circulating in the Paris region, unless they’re carrying 3 or more passengers. Clean cars will also be allowed.


A dense smog covered Paris, France’s capital last week, and levels of PM10 particulates (particles with a diameter of 10 microns or less, directly associated with lung cancer) went way above the levels considered safe by the World Health Organization. According to QZ, the Airparif nonprofit monitoring group predicted PM10 levels would drop to safer levels on Sunday (March 22), but then would rise again (link in French).

The mayor’s office announced at the weekend as of Monday, alternating number plate measurements will take place; also, cars carrying 3 or more passengers will be allowed to circulate, as will emergency cars, hybrids or electric vehicles. About 750 policemen are enforcing the restrictions on Paris’ streets.

While some drivers will find these restrictions extremely annoying, for most of the Parisian population this is a godsend.

“Goodness, it’s calm this morning. What a difference.” said Rosa, a concierge sweeping the front of a building near Boulevard Saint Martin. “I can breathe,” she added.

The Basilique du Sacre-Coeur shrouded in smog as French authorities tackle pollution. Photograph: Xavier Laine/Getty Images

Martin Pietz, a German photographer living in Paris, said he could hardly breathe when cycling to work – something experienced by many pedestrians and cyclists in the city.

“The pollution has become extremely noticeable and worrying. Apart from cutting off my breath, I also find these days that when I get a cough it takes two months rather than two weeks to clear up.”

It is only the third time since 1997 the city authorities have resorted to such emergency measures, but it’s the second time in 2 years – a similar two day ban was imposed in 2014, with positive results and a temporary reduction of PM10 particulates. However, the problem that Paris (and many other major cities in the world right now) is facing is that the huge number of cars in the city cause an increase in the number of particulates and whenever there’s a lack of wind to dissipate them, dramatic conditions ensue – like the ones visible in the images above.

Rather hesitantly, also pushed forth by the public view expressed on social media, the ecology minister agreed to the ban, but not without accusing city mayor Anne Hidalgo of failing to have a “real transport policy” to deal with the pollution problem.

Measures like this might become more and more common as pollution – and especially the number of threatening particulates – continues to rise in many parts of the world. Hopefully, we’ll be able to manage a smooth transition to safer, more eco-friendly cars before this becomes a common reality.





Trees can capture 50% of particulate pollution cities

Trees planted along a city street could screen residents from sun and noise – but more importantly, they can also protect them from the polluted air. A new study has shown that tree leaves can capture more than 50% of the polluting particulate matter – the main source of urban pollution and a trigger for disease.

The trees and birches used in the study. Credit: Environ. Sci. Technol.

The trees and birches used in the study. Credit: Environ. Sci. Technol.

In cities, this type of pollution mostly comes from car exhaust, brake pad wear, and road dust, but it can contain dangerous substances, such as iron and lead. The Environmental Protection Agency classifies particulates depending on size, but virtually all particulates are small enough to be inhaled. Researchers wanted to understand exactly how trees capture this pollution and how they can use this mechanism to our advantage. However, modeling this process is extremely challenging because air flow and particle movement on a street follow complex fluid dynamics.

Barbara A. Maher and her colleagues at Lancaster University, in the U.K., wanted to get some numbers from a real-life situation, so they moved from the lab to the street – analyzing row of eight houses without any trees screening the air. They tracked the amount of dust and particulate matter entering two of the houses as controls and then also used dust monitoring devices to gather data for every 10 minutes for five days. They also used simple wet wipes to gather dust from LED or plasma television screens inside four houses and tested them for metal concentrations.

After they had their initial data, they planted a screen of 30 young silver birch trees in wooden planters in front of four of the houses, including one of the control houses, for 13 days and then gathered data using the exact same techniques. Their results showed 52 to 65% lower concentrations of metallic particles and an overall 50% decrease in the quantity of polluting particulates in the houses.

trees particulates 2

A scanning electron micrograph shows particulate matter captured on the surface of a silver birch leaf.
Credit: Environ. Sci. Technol.

Then, they analyzed the birch leaves with a scanning electron microscope and confirmed that the trees indeed captures the missing pollution. However, it’s still unclear what the trees actually do with it – it can be estimated that at one point or another it reaches the soil, and while that isn’t exactly good either, it’s pretty much the best thing you can do in terms of common urban pollution.

Interestingly enough, oysters do something similar in the marine environment – they’re filter feeders and get a lot of the sediment out of the water, leading to cleaner, clearer water. When the Europeans first came across the Atlantic the Chesapeake bay had so many oysters that the bay was described as crystal clear! As any local or visitor probably knows, that’s really not the case nowadays. Needless to say, just like with trees in most cities of the world, oyster populations are also dwindling – a worrying fact, considering the beneficial effects they have.

Journal Reference:

Barbara A. Maher *Imad A. M. Ahmed , Brian Davison , Vassil Karloukovski , and Robert Clarke – Impact of Roadside Tree Lines on Indoor Concentrations of Traffic-Derived Particulate Matter. Environ. Sci. Technol., Article ASAP. DOI: 10.1021/es404363m